content: /*
  Copyright 2006 Jerry Huxtable
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
     http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  */
  
  package com.jhlabs.image;
  
  import java.awt.*;
  import java.awt.image.*;
  
  /**
   * A filter which performs ordered dithering on an image.
   */
  public class DitherFilter extends PointFilter {
  	
  	/**
       * 2x2 magic square.
       */
  	protected final static int[] ditherMagic2x2Matrix = {
  	 	 0, 2,
  	 	 3, 1
  	};
  
  	/**
       * 4x4 magic square.
       */
  	protected final static int[] ditherMagic4x4Matrix = {
  	 	 0, 14,  3, 13,
  		11,  5,  8,  6,
  		12,  2, 15,  1,
  		 7,  9,  4, 10
  	};
  
  	/**
       * 4x4 ordered dither.
       */
  	public final static int[] ditherOrdered4x4Matrix = {
  	 	 0,  8,  2, 10,
  		12,  4, 14,  6,
  		 3, 11,  1,  9,
  		15,  7, 13,  5
  	};
  
  	/**
       * 4x4 lines.
       */
  	public final static int[] ditherLines4x4Matrix = {
  	 	 0,  1,  2,  3,
  		 4,  5,  6,  7,
  		 8,  9, 10, 11,
  		12, 13, 14, 15
  	};
  
  	/**
       * 6x6 90 degree halftone.
       */
  	public final static int[] dither90Halftone6x6Matrix = {
  	 	29, 18, 12, 19, 30, 34,
  		17,  7,  4,  8, 20, 28,
  		11,  3,  0,  1,  9, 27,
  		16,  6,  2,  5, 13, 26,
  		25, 15, 10, 14, 21, 31,
  		33, 25, 24, 23, 33, 36
  	};
  
  	/*
  	 * The following dithering matrices are taken from "Digital Halftoning" 
  	 * by Robert Ulichney, MIT Press, ISBN 0-262-21009-6.
  	 */
  
  	/**
       * Order-6 ordered dither.
       */
  	public final static int[] ditherOrdered6x6Matrix = {
  		 1, 59, 15, 55,  2, 56, 12, 52,
  		33, 17, 47, 31, 34, 18, 44, 28,
  		 9, 49,  5, 63, 10, 50,  6, 60,
  		41, 25, 37, 21, 42, 26, 38, 22,
  		 3, 57, 13, 53,  0, 58, 14, 54,
  		35, 19, 45, 29, 32, 16, 46, 30,
  		11, 51,  7, 61,  8, 48,  4, 62,
  		43, 27, 39, 23, 40, 24, 36, 20 
  	};
  
  	/**
       * Order-8 ordered dither.
       */
  	public final static int[] ditherOrdered8x8Matrix = {
  		  1,235, 59,219, 15,231, 55,215,  2,232, 56,216, 12,228, 52,212,
  		129, 65,187,123,143, 79,183,119,130, 66,184,120,140, 76,180,116,
  		 33,193, 17,251, 47,207, 31,247, 34,194, 18,248, 44,204, 28,244,
  		161, 97,145, 81,175,111,159, 95,162, 98,146, 82,172,108,156, 92,
  		  9,225, 49,209,  5,239, 63,223, 10,226, 50,210,  6,236, 60,220,
  		137, 73,177,113,133, 69,191,127,138, 74,178,114,134, 70,188,124,
  		 41,201, 25,241, 37,197, 21,255, 42,202, 26,242, 38,198, 22,252,
  		169,105,153, 89,165,101,149, 85,170,106,154, 90,166,102,150, 86,
  		  3,233, 57,217, 13,229, 53,213,  0,234, 58,218, 14,230, 54,214,
  		131, 67,185,121,141, 77,181,117,128, 64,186,122,142, 78,182,118,
  		 35,195, 19,249, 45,205, 29,245, 32,192, 16,250, 46,206, 30,246,
  		163, 99,147, 83,173,109,157, 93,160, 96,144, 80,174,110,158, 94,
  		 11,227, 51,211,  7,237, 61,221,  8,224, 48,208,  4,238, 62,222,
  		139, 75,179,115,135, 71,189,125,136, 72,176,112,132, 68,190,126,
  		 43,203, 27,243, 39,199, 23,253, 40,200, 24,240, 36,196, 20,254,
  		171,107,155, 91,167,103,151, 87,168,104,152, 88,164,100,148, 84 };
  
  	/**
       * Order-3 clustered dither.
       */
  	public final static int[] ditherCluster3Matrix = {
  		 9,11,10, 8, 6, 7,
  		12,17,16, 5, 0, 1,
  		13,14,15, 4, 3, 2,
  		 8, 6, 7, 9,11,10,
  		 5, 0, 1,12,17,16,
  		 4, 3, 2,13,14,15 };
  
  	/**
       * Order-4 clustered dither.
       */
  	public final static int[] ditherCluster4Matrix = {
  		18,20,19,16,13,11,12,15,
  		27,28,29,22, 4, 3, 2, 9,
  		26,31,30,21, 5, 0, 1,10,
  		23,25,24,17, 8, 6, 7,14,
  		13,11,12,15,18,20,19,16,
  		 4, 3, 2, 9,27,28,29,22,
  		 5, 0, 1,10,26,31,30,21,
  		 8, 6, 7,14,23,25,24,17 };
  
  	/**
       * Order-8 clustered dither.
       */
  	public final static int[] ditherCluster8Matrix = {
  		 64, 69, 77, 87, 86, 76, 68, 67, 63, 58, 50, 40, 41, 51, 59, 60,
  		 70, 94,100,109,108, 99, 93, 75, 57, 33, 27, 18, 19, 28, 34, 52,
  		 78,101,114,116,115,112, 98, 83, 49, 26, 13, 11, 12, 15, 29, 44,
  		 88,110,123,124,125,118,107, 85, 39, 17,  4,  3,  2,  9, 20, 42,
  		 89,111,122,127,126,117,106, 84, 38, 16,  5,  0,  1, 10, 21, 43,
  		 79,102,119,121,120,113, 97, 82, 48, 25,  8,  6,  7, 14, 30, 45,
  		 71, 95,103,104,105, 96, 92, 74, 56, 32, 24, 23, 22, 31, 35, 53,
  		 65, 72, 80, 90, 91, 81, 73, 66, 62, 55, 47, 37, 36, 46, 54, 61,
  		 63, 58, 50, 40, 41, 51, 59, 60, 64, 69, 77, 87, 86, 76, 68, 67,
  		 57, 33, 27, 18, 19, 28, 34, 52, 70, 94,100,109,108, 99, 93, 75,
  		 49, 26, 13, 11, 12, 15, 29, 44, 78,101,114,116,115,112, 98, 83,
  		 39, 17,  4,  3,  2,  9, 20, 42, 88,110,123,124,125,118,107, 85,
  		 38, 16,  5,  0,  1, 10, 21, 43, 89,111,122,127,126,117,106, 84,
  		 48, 25,  8,  6,  7, 14, 30, 45, 79,102,119,121,120,113, 97, 82,
  		 56, 32, 24, 23, 22, 31, 35, 53, 71, 95,103,104,105, 96, 92, 74,
  		 62, 55, 47, 37, 36, 46, 54, 61, 65, 72, 80, 90, 91, 81, 73, 66 };
  
  	private int[] matrix;
  	private int rows, cols, levels;
  	private int[] mod;
  	private int[] div;
  	private int[] map;
  	private boolean colorDither;
  	private boolean initialized = false;
  
  	/**
       * Constuct a DitherFilter.
       */
      public DitherFilter() {
  		rows = 2;
  		cols = 2;
  		matrix = ditherMagic4x4Matrix;
  		levels = 6;
  		colorDither = true;
  	}
  	
  	/**
  	 * Set the dither matrix.
  	 * @param matrix the dither matrix
       * @see #getMatrix
  	 */
  	public void setMatrix(int[] matrix) {
  		this.matrix = matrix;
  	}
  
  	/**
  	 * Get the dither matrix.
  	 * @return the dither matrix
       * @see #setMatrix
  	 */
  	public int[] getMatrix() {
  		return matrix;
  	}
  
  	/**
  	 * Set the number of dither levels.
  	 * @param levels the number of levels
       * @see #getLevels
  	 */
  	public void setLevels(int levels) {
  		this.levels = levels;
  	}
  
  	/**
  	 * Get the number of dither levels.
  	 * @return the number of levels
       * @see #setLevels
  	 */
  	public int getLevels() {
  		return levels;
  	}
  
  	/**
  	 * Set whether to use a color dither.
  	 * @param colorDither whether to use a color dither
       * @see #getColorDither
  	 */
  	public void setColorDither(boolean colorDither) {
  		this.colorDither = colorDither;
  	}
  
  	/**
  	 * Get whether to use a color dither.
  	 * @return whether to use a color dither
       * @see #getColorDither
  	 */
  	public boolean getColorDither() {
  		return colorDither;
  	}
  
  	/**
       * Initialize the filter.
       */
      protected void initialize() {
  		rows = cols = (int)Math.sqrt(matrix.length);
  		map = new int[levels];
  		for (int i = 0; i < levels; i++) {
  			int v = 255 * i / (levels-1);
  			map[i] = v;
  		}
  		div = new int[256];
  		mod = new int[256];
  		int rc = (rows*cols+1);
  		for (int i = 0; i < 256; i++) {
  			div[i] = (levels-1)*i / 256;
  			mod[i] = i*rc/256;
  		}
  	}
  
  	public int filterRGB(int x, int y, int rgb) {
  		if (!initialized) {
  			initialized = true;
  			initialize();
  		}
  		int a = rgb & 0xff000000;
  		int r = (rgb >> 16) & 0xff;
  		int g = (rgb >> 8) & 0xff;
  		int b = rgb & 0xff;
  		int col = x % cols;
  		int row = y % rows;
  		int v = matrix[row*cols+col];
  		if (colorDither) {
  			r = map[mod[r] > v ? div[r] + 1 : div[r]];
  			g = map[mod[g] > v ? div[g] + 1 : div[g]];
  			b = map[mod[b] > v ? div[b] + 1 : div[b]];
  		} else {
  			int value = (r+g+b)/3;
  			r = g = b = map[mod[value] > v ? div[value] + 1 : div[value]];
  		}
  		return a | (r << 16) | (g << 8) | b;
  	}
  
  	public String toString() {
  		return "Colors/Dither...";
  	}
  
  }
  
  